Ruby grpc gem indirectly drops support for ruby version < 2.5

[estolfo]

Hi, thanks for this Ruby gem!

I noticed that a new version (3.12.0) of the google-protobuf gem now only supports ruby >= 2.5. The previous version, 3.11, supports ruby >= 2.3.

The grpc gem's dependency on google-protobuf is defined as '~> 3.11'. That means that now the latest version of google-protobuf will be installed with the grpc gem and won't support ruby 2.3 or 2.4 though the required ruby version is defined as >= 2.3.0.

I leave it up to you to decide what you'd like to do :) Whether you want to update your defined required ruby version and the google-protobuf dependency to ~> 3.12 or if you want to restrict the version of google-protobuf installed based on the ruby version.
Or if you want to leave it up to the user to explicitly install google-protobuf version 3.11 when using ruby < 2.5.
Thanks!

[stanley-cheung]

Related to #22978

[alto-ruby]

dropped ruby 2.5 support in #30699